A while back, my wife and I watched 'The Dilemma,' a romantic comedy featuring Vince Vaughn and Kevin James. The pair star as Ronny and Nick, who are best friends and business partners. The duo owns an automobile design firm and hopes to strike it rich by designing an eco friendly car for Dodge.

Things get interesting, however, when Ronny discovers that Nick's wife, Geneva, played by Winona Ryder, is cheating on him with Zip, a younger beefcake hilariously portrayed by Channing Tatum. When Zip discovers Ronny is spying on him and Geneva, a melee breaks out where cars, cameras and pet fish are demolished.

Feeling bad, Ronny goes to Zip's house to apologize. Zip opens the door and pulls a gun on Ronny, who asks if Zip intends to shoot him in broad daylight. Zip says no, but invites Ronny inside, explaining, "I've Googled this. Do you want to know how it works? You come inside and I defend myself. Now, I'm not going to pump six bullets into you. No, that would make me look crazy and out of control. No, I'm going to pump three into you like a calm gun owner would."

While Zip may have shot himself in the foot by inviting Ronny inside his house, the concept he cites actually does exist, and is commonly referred to as the 'castle doctrine.'

Coming on the heels of the concealed carry law, the castle doctrine was adopted into law in Wisconsin in December of 2011. While relatively new in Wisconsin, the doctrine actually dates back to the Roman Republic. In 'The Institutes of the Laws of England,' published in 1628, jurist Sir Edward Coke established as law the common dictum that "an Englishman's home is his castle."

When colonists brought the law to the Americas, they redubbed the doctrine to "a man's home is his castle." The castle doctrine recognizes a person's absolute right to exclude others from his home. When Colorado formalized the castle doctrine into law in 1985, it was also coined the "Make My Day Law," quoting the famous line uttered by Clint Eastwood's "Dirty Harry" Callahan in 1983's 'Sudden Impact.'

Essentially, the castle doctrine shields people from any criminal or civil liability suits for using force, including deadly force, against an invader in the home. The law provides that people using deadly force against anyone unlawfully inside their residence, business or vehicle, are presumed to have acted reasonably. This is true even if the trespasser was unarmed.

Before the castle doctrine was adopted, you could only use deadly force against an intruder if you reasonably believed it was needed to prevent harm to yourself or your family. The castle doctrine doesn't apply, however, if you are using your home or business for criminal purposes, such as operating a meth lab. The protection also doesn't apply to someone who shoots another they knew or should have known was a police officer, firefighter or emergency medical technician.

So before you enter the property of another without permission, as Dirty Harry would say, you need to ask yourself one question: Do I feel lucky?